Flash photographic control system

ABSTRACT

A flash photographic control system for use within a highly automatic reflex camera of a variety utilizing a flash firing circuit in conjunction with a packaged array of flashlamps. The firing circuit ignites the flashlamps sequentially in a predetermined order from first to last. The control system is characterized in electrically isolating the firing circuit during portions of a photographic cycle during which it would otherwise be subjected to spurious signals or noise effects. Additionally, an arrangement is provided wherein the control system overrides the flash firing network under select scene conditions of high brightness.

United States Patent [191 Burgarella et al.

[111 3,820,128 June 25, 1974 1 FLASH PHOTOGRAPHIC CONTROL SYSTEM [75] Inventors: John P. Burgarella, Sudbury; Peter P. Carcia, Reading; Richard C. Kee, Chestnut Hill, all of Mass.

[73] Assignee: Polaroid Corporation, Cambridge,

Mass.

[22] Filed: Feb. 16, 1973 [21] Appl. No.: 333,331

Related U.S. Application Data [63] Continuation-impart of Ser. No. 246,891, April 24,

1972, abandoned.

[52] U.S. Cl. 354/32, 354/149 [51] Int. Cl. G03b 7/08 [58] Field of Search 95/11 L, 11.5 R, 10 CE,

95/53 E, 53 EA, 42, 64 D,

[56] References Cited UNITED STATES PATENTS Years 95/10 CE 3,641,891 2/1972 Burgarella 95/10 CE 3,699,861 10/1972 Burgarella et al. 95/] 1.5

Primary Examiner-Robert P. Greiner [57] ABSTRACT A flash photographic control system for use within a highly automatic reflex camera of a variety utilizing a flash firing circuit in conjunction with a packaged array of flashlamps. The firing circuit ignites the flashlarnps sequentially in a predetermined order from first to last. The control system is characterized in electrically isolating the firing circuit during portions of a photographic cycle during which it would otherwise be subjected to spurious signals or noise effects. Additionally, an arrangement is provided wherein the control system overrides the flash firing network under select scene conditions of high brightness.

44 Claims, 14 Drawing Figures PATENTED JUN 2 5 I974 SHEET 2 OF 9 CURRENT A LATCH MONITOR 5540 552a 552: 5526 POWER "554C SUPPLY 55% FLASH LAMP seen PULSE SWITCHING 568C LOGIC GENERATOR NETWORK PATENTEDJUNZS 1324 3,820,128

SHEET '3 0F 9 u hHA N OE wow mmm Owm PATENTEDJUHZS I974 3 8 20. l 28 SHEU l 0F 9 FLASH MODE cYcLE AMBIENT MODE CYCLE r k A x f E OS RE A INSERT FL SH xP u LAMP ARRAY MECHANISM $835 5 BLADES CLOSE S2 OPEN BLOCKED 204 vIEwING ANP FOCUSING START ENERGIzE SOLENOID I72 DEENERGIZE EXPOSURE MECHANISM FLASH FIRING 238/ CIRCUIT BLADES GLOSE S4 TRANSFER TO C-B I 2I2 ENERGIzE MOTOR ENERGIzE SOLENOID 24o PREEXPOSURE PHASE OPENS S3 OPENS am 32 MONITOR DELAY TIME-OUT 300/ 302 J H N R lZE ID) FLASH DELAY DE E E 6 SOLENO G MECHANISM BLADE SRGGIT TO OPEN CAPIURE S4 TRANSFER TO A-C Y DE-ENERGIzE LIGHT 2IB SOLENOID 24o RESPONSIvE REGULATION 304 i F' ExPOSuRE PHASE IGNITE FLASH TRIGGER FIRES I 30 LAMP I \ZZO i ENERGIzE SOLENOID I72 SuPPRESS l EXPOSURE MECHANISM 308/v LIGHT BLADES cLOSE RESPONSIvE REGULATION I I 84 TRANSFERS TO C"B i l I 224 M0 CR r 310/ FIXED DELAY I T r i DE-ENERGIzE I I FLASH PROCESS COCK REFLEx 3I2 FIRING FILM UNIT 2 COMPONENT cIRcuIT v y 228 S5 cLOSES POST 230 Y EXPOSURE FIG 4 Ex PO SuRE PHASE ME H NISM BLADES OPEN S4 TRANSFER TO CA PATENTED JUN 2 5 I974 sum 5 0r 9 PATENTEU N 7 3.820.128

SHEU 5 OF 9 GATE A GATE 8 GATE 0 GATE D GATE E SOLENOID SOL.|72 MOTOR SOLENOID SOLENOID I72 POWER POWER CONTROL 240 POWER 240 POWER D E DOWN DRIVE DOWN AMBIENT OPERATION EVENT SEQUENCE 0 b c 1" 0 0 t 0 b d Cl e f 1 a e g 1 s, CLOSED SOLENOID I I72 ENERGIZED 84M OOOI 000 OOOI 0000 OO I ExP. MECH. BLADES CLOSED MOTOR ENERGIzED OIOO 000 OI00 0000 00 OI s TRANSFER TO c-a S5OPENS,MOTORSTOPS 0I00 O00 OIII 0000' OOOI S3 OPENS DELAY 2l4 0 I0 0 O0 OI I I O I 0 I COMMENCES o O O o o COMMENCE EXPOSURE OOIOOII 00II 00|0 OOOI S4 TRANSFER TO C- A TRIGGER 358 THRESHOLD REACHED IOII IIO IOII IOIO IOII EXP. MECH. BLADES CLOSED MOTORENERGIZED IIIO IIO IIIO IOIO IOII S4 TRANSFER TO C-B S3CLOSES IIOo I00 IIOI I000 IOOI S CLOSES,S4TRANSFERTOC-A I I00 I00 I I 0I I 000 I OOI FIG. 9-

PAIBHEMWS m4 3.820.128

sum 7 0r '9 s, x525 T AMBIENT OPERATION (P W C? II 4 CA ats s f I L 4 CB 855%: L I L I- III l 85 255% II I 3 OPEN 3 CLOSE TR l G G ER cg i I I I I- TRI5GG2ER HIGH I I I I I FIG. I0 I MOTOR 8E;

LOW I I ON I I I l LATCH I I fi GATE ON I I I I INPUT 0 OFF I I I I GA E ON I INPTUT b OFF I- I GATE l INPUT c 821': I I GATE ON I INPUT :1 OFF L FLASH OPERATION ON 2 OFF NETWORK 504 F NETWORK 54o 'Q QI SOLZIOPWR GATE INPUT e GATE INPUT f GATE INPUT 9 PATENTEnJuIIzs 1974 SHEU 8 UF 9 GATE A GATE B GATE c GATE D GATE E sOLENOID SOL. I72 MOTOR sOL. 240 SOL.24O I73POWER POWER CONTROL POWER POWER DRIvE DOWN DRIVE DowN FLASH OPERATION EVENTSEQUENCE abct 001 obdt cIeft cIegt s CLOSED AND SOLENOID I .ENERGEED'S4 AT OOOI OOO OOOI OOOO OOOI S4CLOSED,TRANSFERS TO c-a 2 MOTORENERGIZED OIOO OOO OIOO OOOO OOOI cIRcuIT 47s DISABLED s 0PENS,MOTOR STOPS 3 S8LENO|D 24OENEROI2ED 0 s OPENS DELAY 2l4 3 I 0 0| I I I 0 0| 0 4 COMMENCES,SOL.240 POWER mm 0 I O 000 O SOLENOID I72 DE-ENERG|ZED 5 INTEGRAT'ONSTARTED OIIOOII OIII OIIO OI O s SWlTCHS TRANSFERSTOC-A ooIo OII OOII OIIO O-IOO AMBIENT OVER-RIDE UNDER I 7 HIGH scENE BRIGHTNESS LEVELS O I I O I O NETWORK 504 TIME-OUT 8 DE-ENERGIZE SOL.I72,F|RE FLASH o O FLASH TIME-OUT BY NGT 540 I 9 EXPOSURE MECHANISM BLADES COMMENCE TO CLOSE s TRANSFERS TO C-B IO FLASH FIRING NOT DE-ENERGIZED I I I0 I I O I l o l l I O I I l I MOTOR ENERGIZED ll S3CLOSES IIOOIOO IIIO IIOO IIOI I2 S5CLOSES,MOTORSTOPS IIOO IOO IIOI IOOo IOOI FIG. ll

. l FLASH PHOTOGRAPHIC CONTROL SYSTEM CROSS REFERENCES TO RELATED APPLICATIONS This is a continuation-in-part of application Ser. No. 246,891, filed Apr. 24, 1972 and now abandoned.

BACKGROUND OF THE INVENTION A thin and compact, yet fully-automatic handheld reflex camera is described in a copending application four United States patent entitled, REFLEX CAM- ERA, by E. I-l. Land, I. Blinow, and V. K. Eloranta, Ser. No. 134,733 filed Apr. 16, 1971, and assigned in common herewith. Although intended for the general photographic market, the automatic camera necessarily is highly complex, being capable of performing a significant number of operational events in the course of a single photographic cycle. For example, during a preexposure phase of such a cycle, the instrumentalities or control components of the camera are called upon to initially fully close an exposure mechanism. This activity secures the exposure chamber of the camera by blocking its taking optical path. The exposure mechanism is driven to its blocking orientation by the continuous energization of a tractive electromagnetic device in the form of a solenoid. When the exposure chamber is secured, a motor is energized for a short period of time to cause the unlatching of a reflex component, thereby causing it to be driven under spring bias into an orientation altering the optical path for purposes of exposing a film unit.

Upon receipt of an appropriate logic signal, an exposure phase of the camera ensues wherein the solenoid drive of the exposure mechanism is de-energized to permit a gradual unblocking of the optical path of the camera. The exposure phase is terminated upon reenergization of the noted solenoid drive and consequent blocking of the optical path.

When the optical path is again blocked, the photographic cycle of the camera continues into a postexposure phase. In the latter operational phase, the exposure mechanism solenoid continues to be energized while the motor again is energized to cock the reflex component into its initial orientation. Additionally, the driven instrumentalities of the camera remove an exposed film unit from the exposure chamber and process it through the driven rolls of a processing station. The post-exposure phase of the photographic cycle ends when the system is shut down to de-energize both the motor and exposure mechanism drive solenoid.

When performing under ambient scene illuminating conditions, the exposure mechanism of the camera is regulated from a light-sensing network having light detecting elements which monitor both scene brightness and corresponding instantaneous exposure values. Preferably, the exposure mechanism is one which continuously varies aperture in the course of a given exposure interval under a program selected to optimize both aperture selection and taking speed. At an appropriate point in time in a monitored exposure interval, the light-sensing network signals the control system of the camera to energize the exposure mechanism solenoid to terminate an exposure. Activation of the lightsensing network is carried out by an electronic form of switching operating in. synchronism with exposure mechanism actuation.

Flashlamp illumination for the noted camera is provided by a lighting system utilizing a multiple flashlamp arrangement wherein a plurality of flashlamps are mounted as an array within a singular disposable package. All of the thus arrayed lamps are oriented for providing scene illumination, when ignited, without recourse to moving or rotating either the flashlamps or their mountings between exposures. Since no relative movement of the flashlamps is involved between exposures, the system includes a firing circuit which sequentially ignites the bulbs in a predetermined order with each photographic cycle. Exposure control for flash mode operation is carried out by a separate control system based upon a follow-focus approach. With this system, the blades of the exposure mechanism are selectively arrested during their opening movement to define a fixed apertural value. This value is automatically determined during focusing procedures, the arresting feature being mechanically linked with the focusing mechanism of the camera. Design of the followfocus mechanism is based upon the inverse square law of light energy propagation in which light intensity is considered to vary inversely with the distance from its source. Actuation of an arresting linkage for the flash control system is provided by a'tractive electromagnetic device, for instance, another solenoid. Once the blades of the exposure mechanism are arrested at an appropriate aperture, the flash firing circuit is actuated to ignite a selected flashlamp and afixed exposure interval ensues which is terminated upon energization of the exposure mechanism solenoid to block the optical path of the camera. A post-exposure phase of the photographic cycle is then carried out.

The use of such firing circuits within the automated camera poses problems not only of avoiding undue power consumption, but also of shielding the sequencing circuit from electrical noise within the control system. Should such noise be excessive, a number of flashlamps might be inadvertently ignited. Such noise may be generated from motor operation, or the like in the course of a photographic cycle.

It additionally is desirable that the exposure control system, when in an ambient illumination mode, be capable of overriding the flash control system under certain photographic circumstances. For instance, under high brightness conditions, the ambient mode control system may providev higher quality photography through a programmed selection of higher relative aperture values. Under such photographic conditions, therefore, the control system of the camera preferably should provide for overriding the flash illumination mode control system while, additionally, preventing the igniting of a flashlamp.

SUMMARY The present invention is addressed to a control system for photographic apparatus in the form of a highly automatic reflex camera of a variety utilizing a firing circuit to selectively and sequentially ignite individual flashlamps within an array thereof. To avoid spurious ignitions of these flashlamps as might be occasioned by electrical noise effects, the control system electrically isolates the firing circuit substantially during all but the exposure phase of its elaborate photographic cycle. For instance, the flash firing circuit is de-energized during periods of motor drive operations as well as during those intervals when the shutter driving solenoid of the camera is energized. By so isolating the operation of the firing circuit, a highly desirable lessening of drain from the limited battery power supply of the camera is realized. The flash firing circuit arrangement of the control system also is utilized in a manner deriving a preference for ambient illumination mode control under scene conditions of high brightness. In this regard, the light sensing network of the ambient illuminational control function of the system is deactivated only following the ignition of a flashlamp. This feature also permits the automatic camera to complete a photographic cycle in ambient mode fashion in the event a flashlamp fails to ignite.

As another feature, the inventive system provides for the derivation of a unique output signal from'its flash firing circuit. This signal is utilized not only for initiating flash interval timing, but also for deriving the noted ambient operational mode preference feature.

A further feature and object of the invention is to provide a photographic control system having an operational mode for flash illumination which performs in conjunction with an operational mode for ambinet illumination over select high brightness scene illumination conditions. With the system, an exposure mechanism which develops progressively varying aperture values during an ambient operational mode is utilized in conjunction with an interceptor arrangement to establish focus responsive aperture values when'operated in a flash illumination mode. The system is operative during the flash illumination mode to actuate the exposure mechanismto terminate an exposure following a fixed interval. Under select scene conditions of high brightness, such actuation is permitted to take place under circumstances wherein the light-sensitive circuit of the camera is disabled only following a select point in time within the exposure phase of a photographic cycle. The control system is operative to disable the lightsensitive circuit of the ambient mode portion of the system only in response to the ignition of a flashlamp. A tractive electromagnetic device such as a solenoid is utilized for purposes of providing a focus-responsive arrest of the exposure mechanism. The control circuit initially de-energizes all electromagnetic devices within the system before the commencement of an exposure phase and, subsequently, de-energizes the arresting solenoid to derive a pulse for actuating the flash firing circuit. When a flashlamp is fired, all electromagnetic instrumentalities are in a de-energized condition.

As another object and feature of the invention, when the noted arresting solenoid is de-energized to effect the ignition of a flashlamp, and following the ignition thereof, a unique signal condition is introduced to the ambient illuminational control features of the system to de-activate the operational thereof. The latter technique of de-activation permits the above-described preference for ambient mode control under high brightness conditions.

Another feature and object of the invention is to provide a control system for a highly-automated photographic camera which includes photographic instrumentalities for carrying out photographic cycles for flash and ambient illuminative modes. These photographic 'cycles includes a pre-exposure operational phase, an exposure operational phase, and a postoperational phase. The instrumentalities further incorporate electromagnetic actuators which are selectively energizable and de-energizable to derive the noted cycle operational phasesin a predetermined order from first to last. The system further includes a firing circuit actuable, when energized, to effect the ignition in predetermined sequence of a flashlamp within an array of such flashlamps. Further included within the system is a control arrangement for selectively regulating the instrumentalities to carry out the operational phases in their predetermined order and which is operative during the noted flash illuminative mode cycle to effect the actuation of the firing circuit when the electromagnetic actuators are in a de-energized condition. The system further may include an arrangement for imparting a preference to ambient illumination mode operation under selectively high scene brightness conditions. This preference is derived in conjunction with a select deenergization of one of the electromagnetic actuators within the noted instrumentalities.

Other objects of the invention will, in part, be obvious and will, in part, appear hereinafter.

The invention, accordingly, comprises the system and apparatus possessing the construction, combination of elements and arrangement of parts which are exemplified in the following detailed disclosure.

For a fuller understanding of the nature and objects of the invention, reference should be had to the following detailed description taken in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a pictorial view of a fully-automatic handheld camera incorporating the control system features of the instant invention, the view having portions broken away or removed to reveal internal structure;

FIG. 2 is a partial pictorial representation of switching features of the camera of FIG. 1 with portions broken away to reveal internal structure;

FIG. 3 is a partial plan view of an exposure mechanism which is incorporated in the camera of FIG. 1;

FIG. 4 is a block logic diagram showing the sequence of events occurring during operational cycles of the camera of FIG. 1; 1

FIG. 5 is a fragmentary detail view of a portion .of the mechanism revealed in FIG. 3;

FIG. 6 is a partial top view showing follow-focus components of the mechanism of FIG. 3 in a stand-bycondition;

FIG. 7 is a partial top view of the follow-focus components of the mechanism of FIG. 3, similar to FIG. 6, but showing an orientation of components during an energized state of the solenoid thereof;

FIG. 8 is a schematic diagram of a control circuit used in conjunction with the control system of the camera of FIG. 1;

FIG. 9 is a truth table or schedule of operational events performed by the control system of the camera of FIG. 1, showing in logic form, the input and output states of gate functions incorporated within the circuit of FIG. 8 as it operates under ambient lighting conditions;

FIG. 10 is an energization status chart for various components of the circuit of FIG. 8 as they operate throughout a photographic cycle under ambient illumination conditions;

FIG. 11 is a truth table or schedule of operational events performed by the control system of the camera of FIG. 1, showing, in logic form, the input and output states of gate functions of the circuit of FIG. 8 when that circuit is operated for flash mode performance;

FIG. 12 is an energization status chart for various components of the circuit of FIG. 8 as they operate in a flash operational mode;

FIG. 13 is a schematic diagram of select components of a flash firing circuit which may be incorporated within the system of the instant invention; and

FIG. 14 is a schematic diagram in greater detail of the flash firing circuit of FIG. 13 illustrating its feedback to overall camera system,

DETAILED DESCRIPTION 1. Camera General Structure Referring to FIG. 1, a fully-automatic reflex camera incorporating the features of the instant invention is portrayed generally at 10. The several articulated housing components of camera 10, including rear wall 12, forward wall 14 and exposure control housing 16 are pivotally associated with a base 18 so as to be foldable thereinto in nesting fashion. When so folded from the erected configuration shown, the camera assumes a thin and compact shape 'suiting'it to be conveniently carried in the pocket of a garment. The specific hinge connections providing for the articulated structure, while not being visible in the figure, are positioned at axes 20, 22, 24 and the lower rear portion of exposure housing 16. I a

When erected for making an exposure, rear wall 12, forward wall 14, and exposure control housing 16 combine in conjunction with an opaque flexible bellows, a fragment of which is illustrated at 26, to define an exposure chamber generallydepicted at 28.

Base 18 includes an inner frame assembly, a portion of which is shown at 30. Inner frame assembly 30, as well as the outward portions of base 18, cooperate to provide structural support for numerous instrumentalities of the camera. For instance, frame is configured to define a receiving chamber for retaining and securing a film laden cassette 32 at the bottom of exposure chamber 28. Cassette 32 is of generally flat, rectangular-shape and contains a stacked assemblage of photographic film units, one of which isshown at 34. Film units as at 34 are arranged for sequential presentation at a light entrance portion of cassette 32which is defined by a ridge 36. The underside of ridge 36 serves as a seat against which the uppermost one of the film units abuts. The forward wall of cassette 32 is formed having an elongate slot 38 disposed thereacross. Slot 38 serves as an egress means providing for the sequential removal of each film unit as at 34. Cassette 32 is also formed having slots or openings in the upward face thereof as at 40. Slots 40 permit the insertion of a component of a pick mechanism which functions to impart initial movements to the film units as they are removed from the cassette. 4

Camera 10 operates in a modified reflex fashion, being convertible between viewing and exposure operational orientations by a reflex assembly, including an operator arrangement formed as a somewhat planar reflex reflecting component 50. Shown at an intermediate position evidenced during a transition from one terminal position to another, the component 50 is configured having a mirror surface 52 mounted upon its underside, and a viewing surface 54, positioned upon or forming its upward surface. In the course of a photographic cycle, reflex component 50 is moved from a viewing position against ridge 36 of cassette 32, where it serves to secure the light entrance portion thereof, to an exposure position abutting against a mirror 56 located upon the inner side of rear wall 12. Movement between the viewing and exposure positions is pivotal, the component being coupled to inner frame 30 at hinges 58 and 60. 7

When component 50 is positioned over ridge 36 of cassette 32 to secure the exposure plane of the camera, a viewing optical path is established. This path extends from a taking lens mounted at 64 in exposure housing 16, through an exposure mechanism depicted generally at 66, which establishes an aperture opening of maximum available width, thence to the reflecting surface of mirror 56 at the rear of the camera and thence to viewing surface 54 at the upward side of component 50. Viewing surface 54 is configured having a texture and optical design facilitating the focusing of the image of the scene to be photographed. This image may be viewed by the camera operator through a collapsible optical viewing assembly depicted generally at .68. A configuration suited for viewing surface 54 is described and claimed in a copending application for US. Pat. Ser. No. 83,030, filed Oct. 22, 1970, by Nathan Gold, entitled, Reflective Imaging Apparatus, and assigned in common herewith, while the assembly 68 and its related internal components are described in detailin a copending application for US. patent by James G. Baker, filed Dec. 15, 1970, entitled, Reflex Camera and Viewing Device, Ser. No. 98,356, and assigned in common herewith.

The exposure optical path orientation of camera 10 is established by pivoting reflex component 50 substantially against the inner surface of. rear wall 12. In this orientation, the optical path nowextends from taking lens 64 and exposure mechanism 66 to mirror 52, positioned on the underside of reflex component 50, thence to the uppermost one of the film or photographic units positioned beneath ridge 36 of cassette 32. Note that such uppermost film unit is located at the exposure plane of camera 10.

, During a viewing operational mode, exposure mechanism 66 defines an aperture of maximum available light transmissability, while reflex component 50 is held in a light-securing position over ridge 36 and, consequently, the exposure plane of camera 10.

Component 50 is retained in its light-securing position by a driven instrumentality operating through hinge 58. Described in detail and claimed in a copending application for US. patent by E. H. Land, l. Blinow and V. K. Eloranta, entitled, Reflex Camera, Ser. No. 134,733, filed Apr. 16, 1971, and assigned in common herewith, the driven instrumentality is regulated from a control system which utilizes the output of a motor 70 to selectively drive an elongate, thin gear train, certain components of which are shown generally at 72, extending along one side of camera 10. The various gear components of gear train 72 are rotatably mounted upon camera 10 between inner frame 30 and an outer plate 74 (FIG. 2). Two reduction ratio circuits are present in gear train 72, one such circuit terminating in a phase control cam 76 which is rotatably driven through one revolution during the course of a single photographic cycle. Cam 76 operates in conjunction with a cam follower 78 positioned upon the inwardly facing side of an elongate ram or actuator 80. Ram 80 is slideably mounted for movement along gear train 72 between the outer face thereof and outer plate 74 and is driveably connected to an input bell crank 82 mounted, in turn, at the rear of camera 10. Input bell crank 82 is connected by a spring linkage to reflex component 50 at hinge 58. As is described in detail in the noted application for patent, Ser. No. 134,733, this spring linkage provides a drive spring feature utilized to move component 50 into its exposure position, as well as an override spring system feature, pennitting cocking operations to proceed, even though component 50 may be stuck in an upward position.

The position of reflex component 50 throughout any given photographic cycle is controlled by select energizations of motor 70 and consequent rotation of phase control cam 76. For instance, when the optical path of camera 10 is in a viewing orientation, cam follower 78 and ram 80 .serve to retain reflex component 50 in its exposure plane securing position over ridge 36 of cassette 32. When reflex component 50 is so retained, cam 76 is in a radial orientation wherein it holds follower 78 and associated ram 80 at a terminal rearward position against the bias exerted by the noted spring linkages utilized'to'drive component 50 and exerted through .input bell crank 82. Acontrolled'energization of motor 70 early in a given photographic cycle causes the gear train 72 to rotate cam 76 to a position whereat follower 78 releases from contact therewith, permitting ram 80 to be driven along with and in correspondence with reflex component 50 into their respective terminal positions. Note, in this regard, that ram 80 and reflex component 50 operate in corresponding synchronism, ram 80 servingas a dynamic tracking device.

Referring additionally to FIG. 2, as ram 80 com mences forward movement in conjunction with the noted release of reflex component 50, a tab 90 extending inwardly therefrom releases from engagement with the insulative cap 92 of a resilient leaf 94 of a switch identified generally as S Switch S additionally includes a resilient leaf 96 which is supportedalong with leaf 94 from an insulative base 98 fixed to outer plate 74 of base 18. Accordingly, the contacts represented by leaves 94-and 96 of switch S are opened substantially in synchronism with the initial movement of component 50 from its viewing position.

The spring biased rotational travel of reflex component 50 about its hinges 58 and 60 from its seated exposure position entails about 37. When reflex component 50 somewhat closely approaches this seated position against rear wall 12 and mirror 56, Le, at about 32, tab 90 contacts the insulative cap 100 of a resilient leaf 108. Station 108 is comprised of two cylindrical rolls 110 and 112 mounted within an access door, the cover of which is shown at 114. Roll 110 of the station is connected with gear train 72 through a drive pinion 116.

At the commencement of the noted second deenergization of motor 70, while roll 110 is being driven, a pick mechanism illustrated generally at 120 is actuated to engage the uppermost photographic film units as at 34, and to move it through forwardly disposed egress slot 38 and into the bite or point of tangency between rotating processing rolls 110 and 112 of station 108. Described in detail in a copending application for U.S. Pat., Ser. No. l7l,l27, by E. H. Land, entitled, Film Advancing Apparatus, filed Aug. 12, 1971, and assigned in common herewith, mechanism 120 includes a carriage assembly 122 which is selectively driven from a cam (not shown) present within gear train 72. Slideably mounted upon inner frame 30 by pin and slot assemblies, a typical one of which is shown at 124, carriage 122 is configured supporting a resilient pick member 126. The outer tip 128 of pick member 126 is configured to extend into and slide along slot 40 of cassette 32. Carriage 122 is spring biased to position tip 102 of another switch depicted generally as S Leaf 102 is normally in contact with a second leaf 104 of switch S and both leaves are supported from an insulative base 106, also fixed to outer plate 74. Serving to monitor the movement of reflex component 50, the open contacts of switch 5;, provide a signal condition evidencing that the component 50 has approached its seated position against rear wall 12.

Following an exposure interval, a post exposure phase of a photographic cycle is carried out by reenergizing motor to drive gear train 72, thereby rotating phase control cam 76. As cam 76 is rotated, contact is reasserted with follower 78 to drive ram rearwardly and cock reflex component 50 into its viewing position. Simultaneously with this cocking activity, a second reduction circuit within gear train 72 functions to drivea processing station shown generally at 128 at the rear of slot 40 of cassette 32. At this position, tip 128 engages the rear edge of a photographic unit 34. When cam driven from gear train 72, the assembly of carriage 122 and pick 126 moves the uppermost one of the photographic film units through slot 40 until it is engaged by the roll of processing station 108. Carriage 122 is latched at its forwardmost position following performance of its pick function and is returned under spring bias to its rearward station at the completion of the photographic cycle.

Photographic units 34 are processed by the pressure applied from rolls and 112 of processing station 108 as they are drawn therethrough. Described in detail in a U.S. patent by E. H. Land, No. 3,145,644, these units are structured to contain a processing fluid which is spread therewithin to cause the formation of a visible positive image.

2. Camera Exposure Mechanism The exposure control system of camera 10 is called upon to perform a number of operational steps in the course of a photographic cycle. For instance, it is required to operate exposure mechanism 66 in a manner establishing an aperture opening of maximum width or light transmissibility for viewing and focusing purposes. During the conversion of the optical path of camera 10 from a viewing orientation to an exposure orientation, mechanism 66 is retained in a fully closed condition to secure exposure chamber 28. Further, in the courseof an exposure interval, mechanism 66 and its related control provides for a dual exposure parameter regulation in which both aperture and exposure interval are controlled in accordance with a predetermined, optimized photographic program. For instance, under such a program, relative aperture should be selected automatically to optimize depth of field, while exposure interval is selected to maximize taking speed.

Looking additionally to FIGS. 3 and 5, exposure mechanism 66 is shown to be formed having two blades, and 142, which slidably ride in a track (not shown) mounted within exposure housing 16. Each blade, 140 and 142, is formed having a teardrop shaped apertured opening as shown, respectively, at 144 and 146. Additionally, the blades are formed having secondary openings, shown respectively at 148 and 150, (FIG. 1) which move in synchronism with openings 142 and 144 before the detecting elements of a photosensing network positioned behind an entrance optical assembly 152. Openings 144 and 146 of respective blades 140 and 142 are positioned for movement across the optical path of camera as it is established at taking lens 64. Depending upon the positions of blades 140 and 142, openings 144 and 146 symmetrically overlap to define selectively varying aperture sizes. Secondary openings 148 and 150 are configured somewhat in correspondence with the contours of respective openings 144 and 146 and also move in mutual symmetry over the optical path of the light sensing network of the control system of thecamera.

Blades 140 and 142 are moved in mutual symmetry as a result of their connection with a walking beam type actuator shown at 154. Walking beam 154 is formed having a centrally disposed hub portion 156 which is journalled for rotation about an upstanding stud (not shown) extending from the rear casting 158 of exposure control housing 16. Elongate slots as at 160 and 162 (FIG. 3), are formed in the tip portions of walking beam 154 for the purpose of providing connection with pins 164 and 166 extending, respectively, from blades 140 and 142. I

A bias urging walking beam 154 to move blades 140 and 142 into a closed orientation is provided by a closing spring 168 (FIG. 3). Wound about hub 156, the stationary end of spring 168 is grounded against a pin 170 extending from rear casting 158, while its moving end is wound about the lower portion of walking beam 154.

Actuation of blades 140 and 142 for purposes of controlling exposure as well as for securing the exposure chamber 28 is carried out by a tractive electromagnetic device present as a solenoid 172. Described in detail in a copending application for US. Patent by C. C. Petersen, entitled Tractive Electromagnetic Device Ser. No. 245,884 filed Apr. 21, 1972, and assigned in common herewith, solenoid 172 is formed having an excitation winding 174 which is wound about a bobbin 176 attached, in turn, to a U-shaped frame 178. A cylindrically shaped plunger 180 is slidably mounted within a corresponding central opening within bobbin 176 and the composite assembly is fixed to rear casting 158.

Plunger 180 is biased to move outwardly from its retracted position within excitation winding 174 by an opening spring 182. Present as a spirally wound compression spring of relatively high spring index, opening spring 182 is constrained between frame 178 and an outer striker cap 184 fixed to the outer extremity of plunger 180. Cap 184 is positioned to establish an abuttable contact with an upstanding pin 186 extending from the lower portion of walking beam 154. The loading or force value characteristics of spring 182 are selected as being greater than the loading characteristics of closing spring 168. Accordingly, when excitation winding 174 is de-energized, spring 182 urges plunger 180 outwardly to contact pin 186 and drive walking beam 154 toward positions establishing progressively widening apertures. When plunger 180 is fully extended, blades 140 and 142 define an opening of maximum aperture width, as shown in FIG. 3. Upon energization of excitation winding 174, plunger 180 is retracted thereinto at a rate negating the noted abutting contact force between cap 184 and pin 186. As a consequence, walking beam 154 is permitted to rotate under the bias closing spring 168 to drive blades and 144 into an aperture closing orientation as shown in FIG. 1. The retracted orientation of spring 182 and cap 184 is shown in FIG. 5 in solid line fashion, while their extended positions under a de-energized state of winding 174 is shown with identical numeration marked with a prime A detailed description of the solenoid driven exposure mechanism shown at 66 .is presented in a copending application for U.S. Patent by L. G. Douglas, entitled Electromagnetically Actuated Exposure Control Mechanism filed Apr. 2I, I972, Ser. No. 245,801 and assigned in common herewith.

Operating in conjunction with solenoid 172 is a single throw double pole switch designated S As shown more clearly in FIG. 5, switch'S is formed having an upstanding insulated base 188 fixed, in turn, to frame 178. Base 188 supports an elongate contact rod 190, the upwardly extending portion of which is configured to wipe across two separate conducting surfaces 192 and 194. Formed 'of conductive and resilient material and connected in cantilever fashion with screw 196 to base 188, the rod 190 is normally biased to move out wardly into contact with conductive surface 194. When solenoid 172 is energized and its plunger is retracted, however, a pin 198 extending laterally from cap 184 drives contact rod rearwardly to wipe against and make electrical contact with conducting surface 192. Conducting surfaces 192 and 194 are relatively closely spaced such that electrical contact is effected with surface 192 when plunger 180 is closely proximate its fully retracted and seated position. Conversely, contact rod 190 effects electrical contact with conducting surface 194 very rapidly upon deenergization of solenoid 172. Preferably, this contact is made before shutter blades 140 and 142 are permitted to define an aperture opening.

3., AMBIENT CYCLE OPERATION Referring additionally to FIG. 4, the operational events sequence defining a photographic cycle as camera 10 operates under ambient illuminational conditions is displayed in block logic form. For instance, upon erecting camera 10 to the configuration shown in FIG. 1, the operator views and focuses a scene to be photographed through optical assembly 68. To optimize this viewing, blades 140 and 142 of exposure mechanism 66 are fully opened as depicted at function block 204. Additionally, the exposure plane of the camera is blocked by reflex component 50 as it is positioned over ridge 36 of cassette 32. This securing of the exposure plane is depicted by function block 206. F 01- lowing viewing and focusing, a photographic cycle is commenced with the depression of a start button 208 located on a forward face of control housing 16 (FIG. 1). Depression of this button closes appropriate switching to energize the control system of a camera which, in turn, effects the energization of winding 174 of solenoid 172. When so energized, solenoid 172 retracts plunger 180, permitting closingspring 168 to drive walking beam 154 in a direction moving blades 140 and 142 into the closed position shown in FIG. 1. The initial closure of exposure mechanism blades 140 and 142 upon depression of start button 208, as depicted at function block 210, commences a pre-exposure phase of the photographic cycle. The extent of this phase and succeeding ones is bracketed and labelled in FIG. 4.

As exposure mechanism blades 140 and 142 reach their fully closed position and as plunger 180 closely approaches its fully seated position, contact is made between rod 182 and conducting surface 192 of switch 8,. As depicted in function block 212, when such contact is made, the control system of the camera operates to release reflex component 50. To carry out this release, the control system energizes motor 70 for a short period of time to actuate gear train 72, thereby driving phase control cam 76 a sufficient amount to release ram 80 for movement. When so released, ram 80 permits the drive springs associated with hinge 58 to move both the ram 80 and reflex component 50 toward their terminal exposure phase positions.

As reflex component 50 pivots to about 32 of rotation, tab 90 of ram 80 contacts tip 100 of resilient leaf 102 of spring S Switch S is opened. Serving as a transducer stage for monitoring the movement of reflex component 50, the. open contacts of switch 5;, provide a signal condition evidencing that component 50 has approached its seated position. When switch S is opened, the control system of the camera provides a delay function as indicated at block 214. This delay is predetermined, beingselected to accommodate for any dynamic instability'such as bouncing or the like which reflex component'50 may exhibit against itsseated position in rear wall 12.

Upon appropriate time-out of the delay. function generated from switch S the control system is signalled to start the exposure phase of its photographic'cycle. This phase is commenced upon the deenergization of excitation winding 174 of solenoid 172, which permits spring 182 to drive walking beam 154 against the bias of spring 168 toward positions defining relative apertures of progressively decreasing values. At the commence- .ment of such movement, contact rod 190 of switch S moves into contact with conductive surface194. The commencement of movement of blades 140 and 142 towards the open positions as well as switch S, actuation is depicted at block 216.

Simultaneously with the opening movement of blades 140 and-142, the light sensing network of the control system evaluates scene lighting from entrance assembly 152 as it is affected by moving openings 148 and 150. (FIG. 1) This light responsive regulation function is depicted at block 218. When the control system evaluation function determines that the exposure interval should be terminated, a trigger within the circuit thereof is fired, as depicted at function block 220, and excitation winding 174 is again energized to cause the retraction of plunger 180 and rapid closure of blades 140 and 142. This exposure terminating function concludes the exposure phase of a given photographic cycle and is depicted at block 222. As plunger 180 again reaches its fully retracted position, switch S is again actuated such that-rod 190 moves again into contact with conducting surface 192. The postexposure phase of the photographic cycle now commences with the re-actuation of switch S Energization of the excitation winding 174 of solenoid 172 continues throughout the post-exposure phase in order to secure exposure chamber 28 during ensuing movement of reflex component 50. The latter reorientation of component is carried out by reenergizing motor 70 to drive gear train 72 and thereby and 112. The processing feature is rotate phase control cam 70. This second energization of motor is depicted at block 224. As cam 76 is rotated, contact is reasserted with follower 78 to drive ram 80 rearwardly and cock reflex component 50 towards its viewing position as depicted at block 226. Simultaneously with the above-described cocking activity, the second reduction circuit of gear train 72 drives roll of processing station 108 and actuates pick mechanism 120. As described earlier, mechanism serves to urge up the uppermost exposed film unit from cassette 32 and into the bite of rotating rolls 110 depicted at function block 228.

At the termination of the above-described cocking and processing functions, tab 90 of ram 80 will have reasserted contact with cap 96 of switch S to cause the closure thereof as depicted at function block 230. As a consequence, the control system of camera 10 is antomatically shut-down to terminate the photographic cycle. Such shut-down de-energizes the excitation winding of solenoid .172 to permit blades and 142 to open under the bias of opening spring 182. The latter event is depicted in FIG. 4' at function block 232. As blades 140 and l42'commence to move toward their open positions, contact rod 182 of switch S returns to its unloaded orientation in contact with conducting surface 194.

4. FLASH CYCLE OPERATION In the discussion above, a photographic cycle of camera 10 has been described as -it relates to operation under ambientlighting conditions. To operate the camera with artificial or flash illumination, a packaged linearly arrayed multiflashlamp assembly such as that shown in FIG. 1 at 234 is mounted upon exposure housing 16. When so mounted, assembly 234 serves to arm or activate a flash control logic within the control system of the camera by closing a switch (FIG. 8) designated S the discussion to follow. F IG. 4 also depicts a resulting flash mode photographic cycle, the noted control logic activation occasioned from insertion of flash array 234 and closure of switch S being depicted by function block 236. The flash mode cycle includes a. series of additional or substitute operational events which compliment or bypass those suited for ambient performance. For instance, following viewing and focusing and depression of start button 208, the excitation winding 174 of solenoid 172 is energized to close exposure'mechanism blades 140 and 142 as shown at function block 210. As plunger of solenoid 172 moves into its fully retracted position, contact rod of switch S moves out of contact with conducting surface 194 to effect the tie-energization of a flash firing circuit within the control system. This function is depicted at 238. As rod 190 reaches conducting surface 192, motor 70 is energized to release reflext component 50 as shown at function block 212. With the resultant opening of switch the excitation winding of a second, follow-focus solenoid 240, forming part of exposure mechanism 66, is energized. Such energization is depicted at function block 242 in FIG. 4. Solenoid 240 represents the drive component of a follow-focus Y phy, Ser. No. 168,671, filed on Aug. 3, 1971 and assigned in common herewith. This follow-focus mechanism provides a mechanical coupling between the focusing system of camera andthe aperture adjusting feature of exposure mechanism66.

Referring to FIG. 3, taking lens 64 is mounting inan externally threaded bezel, the threaded periphery of which is depicted in phantom in 244. Selective rotation of this bezel serves to provide a focusing function for the camera. Periphery 244, in turn, is threadibly engaged with the teeth of an idler gear 246 which is mounted for rotation about an upstanding stud 248 fixed, in turn, to rear casting 158. Gear 246 is retained upon stud 248 by a flat faced screw 250. which is threadibly engaged with stud 248. Also threadibly engaged with idler gear 246 is a manually adjustible focusing wheel. 252, the topmost periphery of which extends through the cover of exposure control housing 16 to permit operator access thereto. Focusing wheel 252 is mounted for rotation upon the collar of a screw 254 extending therethrough and into rear casting 158.

Referring additionally to FIGS. 6 and 7, solenoid 240 is configured having an excitation winding 256 mounted upon a bobbin 258 which, in turn, is supported upon a U-shaped frame or bracket 260. Frame v260 is fixed to rear casting 158 in a manner positioning solenoid 240 behind focus wheel 252 and above solenoid 172. When taking lens 64 is appropriately focused, the follow focus components of mechanism 66 position an interceptor linkage 262 at a location whereat a cam surface 264 formed thereupon may arrest the opening movement of blades 140 and 142 at a position defining a proper aperture value. Linkage 262 is pivotally connected by an axle 266 through inwardly depending flanges of a cam follower 268. A slot 270 formed within follower 268 provides for the slidable To move cam surface 264 of interceptor linkage 262 into an intercepting or arresting position, linkage 262 is driven inwardly such that surface 264 is positioned to intercept a pin 276 extending from walking beam 154. Note that pin 276 is formed having an annular shaped flange portion 276 at its outer tip. An intercepting orientation for linkage 262 is depicted in FIG. 7, while a standby or non-intercepting orientation for linkage 262 is illustrated in FIG. 6. Linkage 262 is biased into the latter orientation by a plunger 280 extending from a portion of rear casting 158. Outward bias is imparted to plunger 280 by a compression spring 282. The noted bias exerted from plunger 280 is applied against the inner face of an arm-type extension 284 of linkage 262. Contact with the opposite face of arm 284 is provided by a pull-down bar 286. Pull-down bar 286 is loosely pinned to an extension 288 of frame 260 by a rivet 290. Bar 286 also is pivotally coupled to the internally disposed plunger 292 of solenoid 240 by a connector 294. Thus configured, when the excitation winding 296 of solenoid 240 is energized, plunger 292 is retracted therewithin to draw pull-down bar 286 inwardly and, in turn, urge linkage 262 inwardly against the bias of spring 282.

.142 commence to define progressively enlargening aperture widths until such time as pin 276 of walking beam 154 is captured by contact with camming edge 264 of interceptorlinkage 262. The latter capture .as well as a delay feature suspending further operational events within the exposure phase is indicated at function block 300. As plunger 180 moves outwardly from its fully retracted position, contact bar 190 of switch S moves into contact with conductive surface 194..As noted at block 302, this switching activity energizes the flash firing circuit of the system, however, the system is not committed to a flash mode cycle at this point. Accordingly, the light responsive regulation function described in connection with block 218 continues to operate in normal fashion. At the termination of the flash delay described in connection with block 300, solenoid 240 is de-energized,'as shown at block 304. No exposure mechanism blade movement ensues, inasmuch as the outer flange portion 278 of pin 276, operating in conjunction with the bias exerted from spring 182, maintains the interceptor link 262 at its arrested orientation. When solenoid 240 is deenergized as described at 304, a pulse is generated which is utilized to actuate the flash firing circuit of the system to ignite a select flashlamp as indicated at block 306. Only when such a flashlamp has been successfully ignited is the light responsive regulation operation of the system, as described at block 218, suppressed. Such suppression is depicted at block 308. Assuming that a'flashlamp has been successfully ignited, a fixed delay, as depicted at 310, ensues to establish an exposure interval corresponding with the light generation time of the fired flashlamp. At the conclusion of delay function 310, a trigger is fired, as described at 220, to energize solenoid 172 to close blades 140 and 142. As blades 140 and 142 reach their terminal positions, pin 192 within solenoid plunger 180 again transfers contact rod 190 of switch S, into contact with conducting surface 192. This activity serves to de-energize the flash firing circuit as depicted at function block 312.

The latter activity at switch S also serves to energize motor 70 to commence the post exposure phase of the photographic cycle, as shown at function block 224. The post exposure phase of the flash mode cycle continues with the same sequence of operational events as performed under ambient mode conditions. These events are discussed above in connection with function blocks 224 through 232.

5. CONTROL CIRCUIT IN GENERAL Referring to FIGS. 8 and following, a schematic diagram for a control circuit suited to regulate the instrumentalities heretofore disclosed is provided. Truth tables and related energization state diagrams also are provided for purposes of graphically illustrating the performance of components within the circuit. The circuit of FIG. 8 includes a series of multi-function GATES designated A-E. The inputs and outputs for these GATES are depicted in Boolean enumeration in the noted truth-tables. For purposes of understanding the tabulations within these figures, as well as to facilitate the description to follow, when the inputs or outputs of the listed components are at ground reference potential, they are referred to as low and, additionally, such input or output may be digitally identified as 0. Conversely, when these inputs and outputs assume or approach the voltage status of the power supply of the control circuit, they are referred to as being high and are given the binary designation 1. The operational events as tabulated and numbered in the truthtables are again identified by the same encircled numeration in the corresponding energization state diagrams. In these diagrams, the status of switches -8 of the circuit as well as the energization states of various components thereof are shown in comparative timescale fashion. It may be noted further, that certain of the GATE input terminals receive common signals. These common signal terminals are identified by the letters a-g. Additionally, the outputs of GATES A-H are identified, respectively by the letters t -t 6. CONTROL CIRCUIT -AMBIENT CYCLE Looking to FIGS. 8, 9 and 10, the circuit arrangement for controlling camera 10 under ambient lighting conditions is illustrated. As noted earlier, a photographic cycle is commenced with the depression of start button 208. This depression serves to close a switch designated as S in FIG. 8. Closure of switch S, connects a primary power line 338 which is connected with the positive terminal'of a battery 340. The opposite terminal of battery 340 is connected by a line 342 to ground. Thus connected, primarypower line 338 serves .to energize a latching network depicted functionally by block 344. Described in detail and claimed in a copending'application for United States patent entitled, Control System For Photographic Apparatus, by J. P. Burgarella, P. P. Carcia and R. C. Kee, Ser. No. 2l3,'3l7, filed Dec. 29, 1.971, and assigned in common herewith, network 344 operates under two energization states. The first of these states permits the operator of camera 10 to abort a photographic cycleuntil such time as switch S is opened, as discussed in connection with function block 212 of FIG. 4. Following the opening of switch S a second energization state at network 344 permits a continuous powering of the circuit from line 345, even though the contacts of switch S, are separated.

The output of latching network 344 is present at a power distribution line 346 which, in turn, is connected to a branch power line 348. Branch power line 348 is connected to a second branch power line 350 and these two lines serve to power and assert initial control conditions over the various gates and components within the entire circuit.

These conditions, as they exist at the commencement of a photographic cycle, are tabulated at Event No. 1 in FIG. 9 and are represented by a family of energiza tion curves in FIG. 10. As described in connection with functionblock 210 of FIG. 4, the initial operational event is that of energizing the excitation winding 174 of solenoid 172. This is carried out by asserting select input conditions to the input terminals of multifunction GATES A and B. Looking to these inputs, input terminals a, commonly connected by line 354, exhibit an initial low status by virtue of their connection along line 356 to the output of a trigger circuit 358. Trigger 358 may be of a conventional design, for

16 instant, a Schmitt-type having a normally conducting output state and a normally non-conducting input state. These states operate to reverse their conductive states very rapidly upon receipt at the input stage of a signal which is at least equal to a predetermined triggering reference or threshold level. Energized from branch power line 348 through line 360 and coupled to ground through line 362, the output at line 356 of trigger 358 remains low until a signal above the noted triggering reference level is received at any of its input lines, for instance, at line 366. Upon receive of such signal, the output at line 356 assumes a high status. Such input, as derived at line 366, is developed from a control signal generated at a light-sensitive exposure control network designated generally at 368.

Gate input terminal b of GATE A evidences a low state by virtue of its connection through line 370 and limiting resistor 372 to ground. Additionally, this low status is permitted as a result of the connection of line 370 through lines 374, 376 and 378 to switch 5,. Switch S, corresponds with that described in conjunction with the earlier figures and is shown havinga common terminal c contact rod and alternate contacts A and B. When switch 5., assumes c'ondition C-A, it is considered to be in position wherein contact rod 190 is in contact with conducting surface 194, as discussed in connection with FIGS. 3 and 5. When switch 8., assumes condition C-B," it is considered to be in the orientation described in the noted figures wherein contact rod 190 is in contact with conducting surface 192. Inasmuch as switch S is normally in a GA condition at the commencement of a photographic cycle, line 378 is open-circuited. At such time as switch 5., assumes a C-B condition, line 378 is energized through line 364 from primary power line 338.

Gate input terminal c of GATE A is coupled through line 380 and line 382 to the corresponding common input terminals of GATE B. The initial low status of common input terminals 0 is derived as a result of the connection of line 382 through line 384 to the output 386 of a trigger 388. Similar to trigger 358, the output of trigger 388 is normally low and will assume a high status in response to the receipt of a signal above a predetermined triggering or threshold value at its input 390. j

Trigger 388 is energized from branch power line 350 through line 392 and is coupled to ground through lines 394 and 396. Representing the triggering components of the delay function described in connection with function block 214 of FIG. 4, trigger 388 serves to retain common input terminals c at a low state during the pre-exposure phase of a photographic cycle. Note that this low input condition represents a signal from the electrical-mechanical interface of the control system that reflex component has not been elevated to a position proximate that required for initiating the exposure phase of a photographic cycle.

' With the assertion of the above-described input logic, the resultant initial output, t, of GATE A present at line 398, is high and is imposed at the base of an NPN transistor Q The emitter of transistor 0 is coupled along line 400 to ground while its collector is connected to line 402. Line 402, in turn, connects the excitation winding 174 of solenoid 172 to primary power line 338. The high status at line 398 serves to forward bias the base-emitter junction of transistor 0,,

thereby energizing winding 174 to cause exposure mechanism 66 to block the optical path of camera 10, as described in connection with function block 210 of FIG. 4. The output t of GATE B is low at the commencement of a photographic cycle and is coupled through a current limiting resistor 404 and line 406 to line 402. GATE B serves apowering down function wherein solenoid 172 is energized at a lower current level when the plunger 180 thereof gains its fully retracted position. To carry this out, GATE B diverts solenoid energizing current through limiting resistor 404. When transistor is forward biased, however, this diversion through resistor 404 is insignificant. The powering down feature of the control system is described and claimed in a copending application for United States patent by C. H. Biber and E. K. Shenk, entitled, Photographic Apparatus with Solenoid Powered Instrumentalities, Ser. No. 163,948, filed July 19, 1971, and assigned in common herewith.

Solenoid 172 being energized, blades 140 and 142 are driven to their fully closed position. When this position is reached, contact rod 190 of switch S, will have been transferred to derive a GE condition.

As noted at Event No. 2 of FIGS. 9 and l0,'this condition of switch S alters the b input terminal state at line 370 from a low to a high, thus, the output at t, becomes low. A low state at output t serves to remove the forward bias at transistor Q. As a consequence, the earlier described power-down function performed by GATE B continues the energization of winding 174 at a lower current level. This input terminal alteration also changes the output t of GATE C. While Event No. 1 is being carried out, the output 1 at line 408 of GATE C is high. This high output is established as a result of a low present at line 410 and introduced to input terminal a. Line 410 is coupled to line 354, the latter line providing a common coupling of the corresponding inputs of GA TES A and B. Gate input terminal d of GATE C remains low in consequence of its connection through lines 412, 414 and closed switch S to ground. As catalogued at Event No. 2 of FIGS. 9 and 10, inasmuch as input tenninal b of GATE C is connectable to primary power line 338 from lines 364, 378 and switch 8., when in a C-B condition, its status is now altered from a low to a high" state. The resultant low output i of GATE C, when introduced through line 408, signals a motor control function 416 to energize motor 70. Control function 416 is energized from primary power line 338 through line 418 and is coupled to ground through line 420.

As discussed in connection with function block 21 of FIG. 4, the resultant energization of motor 70 effects the release or unlatching of reflex component 50, thereby enabling a spring drive mechanism to move it away from its viewing position. At the commencement of this movement, when component 50 remains closely proximate its viewing position, tab 90 of ram 80, moving in corresponding synchronism with reflex component 50, releases from engagement with insulative cap 92 of leaf 94 to open switch S As disclosed in Event No. 3 in FIGS. 9 and 10, the opening of switch S alters the status of input terminal d of GATE C to a high" condition and the resultant outputs t of the GATE becomes high. A high status at line 408 serves to signal motor control function 416 to de-energize motor 70. As a consequence, drive to gear train 72 is halted.

The opening of switch S and resultant alteration of the status of input terminal d serves to signal latching network 344 to assume its second energization state, thereby committing the control system to the completion of photographic cycle. Connection between input line 412 and network 344 is made through resistor 422, line 424 and line 426.

As reflex component approaches a location proximate its seated exposure position, ram acting through tab 90, contacts insulative cap to open switch S Represented as Event No. 4 of FIGS. 9 and 10, the opening of switch 8;, serves to activate an R-C timing network identified generally at 430. This network serves to impose the delay described in connection with function block 214 in FIG. 4.

Formed of a timing resistor 432 and a timing capacitor 434 coupled within line 436 between line 396, ground and branch power line 350, network 430 serves to delay the commencement of the exposure phase of a photographic cycle. This delay is selected in accordance with a time constant sufficient to permit reflex component 50 to fully seat at its exposure position.

Network 430 is activated upon removal of a shunt about capacitor 434 which is constituted by a line 438, connected from a point intermediate capacitor 434 and resistor 432, to ground through a diode 440 and switch S Diode 440 serves to isolate line 438 from spurious signals and the like.

Following the time-out of network 430, a threshold signal is developed at input 390 of trigger 388. As a consequence, trigger 388 alters its output at line 386 to a high status. This high status is introduced from line 384 to lines 380 and 382 to simultaneously alter the state of all common gate inputs 0 to d high or 1 status. Such alteration changes the output t of GATE B to high state, thereby abruptly terminating current flow in line 402, with the consequence of deenergizing excitation winding 174 of solenoid 172. As described in connection with function block 216 of FIG. 4, the exposure phase of a photographic cycle begins as blades and 143 of exposure mechanism 66 commence to open under the bias of opening spring 182. As solenoid plunger commences to move from its retracted position, contact rod of switch S rapidly transfers to cause the switch to again assume its C-A condition. The state the switch to again assume its C-A condition. The state of common gate input b alters from a high to a low state as depicted at Event No. 5 in FIGS. 9 and 10.

In addition to effecting the de-energization of excitation winding 174, the signal change in line 382 also is introduced through an inverter 442 to activate an electronic switch shown functionally by block 444. Described in detail and claimed in a copending application for United States patent by E. K. Shenk, Ser. No. 213, 289, tiled Dec. 20, 1971, entitled, Exposure Control System Incorporation Solid State Switching to Enable a Light-Sensitive Network, and-assigned in common herewith, when triggered, switch 444 removes a shunt established by lines 446 and 448 across a timing capacitor 450. The removal of this shunt activates exposure control network 368, thereby providing the light-responsive regulation function described in connection with block 218 of FIG. 4 and represented as Event No. 5 in FIGS. 9 and 10.

Network 368 includes a photovoltaic cell 452, positioned within camera behind openings 148 and 150 of exposure mechanism 66 and connected to the input of an operational, differential-type amplifier 454 by lines 456 and 458. Timing capacitor 450 is coupled within a feedback path between output 460 of amplifier 454 and its input at line 456.

Described in greater detail in US. Pat. No.

3,620,143, the output of this light-sensing arrangement at line 460 represents an integrated valuation of scene lighting as witnessed at the optical path of camera 10. This output is varied in accordance with the sensitrometic properites properties of film being exposed by a second amplification stage 462. Amplification stage 462 operates in conjunction with a gain adjusting variable resistor 464 and a calibrating resistor 466, the latter being positioned within a feedback path line 468. Power supplies forboth amplifier 454 and 462 are provided from branch power line 348 and line470, while ground connections for the amplifiers, respectively, are provided through lines 472 and 474. The adjusted output from network 368 is presented alongline 366 to trigger 358. When the signal value at line 366 reaches the threshold level of trigger 358, the output thereof at line 356 converts from a low to a high state, This conversion is represented in FIGS. 9 and 10 as operational Event No. 6. As displayed in those figures, the resultant high output at line 356 alters the status of common gate input terminals a to a corresponding .high status. The resultant outputs of GATES A and B are inverted. For instance, output t, of GATE A is changed to high status and output t of GATE B is changed to a low status. A high output at line 398 serves to forward bias the base-emitter junction at transistor 0,, thereby energizing solenoid winding 174 from line 402. Solenoid 172 then operates to block the optical path of camera 10 by closing blades I40 and 142. As plunger 180 of solenoid 172 .reaches its fully-retracted position, pin 192 extendingtherefrom moves contact rod 190 to alter switch S to a .C-B condition. The exposure phase of the photographic cycle is terminated.

With the noted orientation of switch the postexposure phase of the photographic cycle ensues. The status of input terminals b at GATES A and C converts from a low" to a high state. As tabulated and displayed at Event No. 7 in FIGS. 9 and 10, the latter input alteration changes output I, to a low state to remove the forward bias at transistor 0,. Similar to Event No. 2, the power-down function provided by GATE B is carried out. Further, the output t of GATE C changes to a low status, thereby activating motor control function 416 to, in turn, energize motor 70. As discussed earlier in connection with function blocks 226 and 230 of FIG. 4, when thus energized, motor 70 rotates cycle phase cam 76 to drive ram 80 rearwardly, thereby cocking reflex component 50 to its viewing position. Of particular note, during the postexposure phase, the output of trigger 358 at line 356 remains low and will be seen to serve as a controlling logic input requiring the completion of the final phase of the photographic cycle. Note in this regard, that common gate input a of GATES A, B and C has reverted to a high state.

As ram 80 is driven rearwardly in the course of the post-exposure phase of the photographic cycle, pick assembly 120 is actuated to draw a photographic unit 20 as at '34 from cassette 32 and move its forward edge into the bite of rotating processing rolls and 112 to process the unit and drive it out of the receiving chamber of camera 10. Such activity is depicted in FIG. 1.

As reflex component 50 is cocked away from its exposure position, switch S is again closed, thereby reactivating the shunt imposed by line 438 about timing capacitor 334. The output at 386 of Trigger 388. returns to a low status to, in turn, change the state of common gate input terminals c to a low status see Event No. 8 of FIGS. 9 and 10).

When reflex component 50 moves to a location closely proximate its seated viewing position, tab 90 of ram 80 contacts insulative cap 92 of switch S to urge leaf 94 into engagement with leaf 96. Displayed as Event No. 9 in FIGS. 9 and 10 and discussed in connection with function block 230 at FIG. 4, this switching action signals the control circuit that the exposure plane is again secured and that a photographic cycle may be concluded. When Switch S is closed, the condition of gate input terminal d alters from a high to a low status to, in turn, change the output t at line 408 to a high status, thereby signaling motor control function 416 to stop motor 70.

When closed to terminate a photographic cycle, switch S also imposes a quenching signal upon latching function 344 from along lines 414, 412, 424 and 426. As a consequence, the entire circuit is de-energized thereby permitting the de-energization of excitation winding 174 of solenoid 172. The latter de-energization is carried out if switch S is open and level to permit exposure mechanism blades and 142 to be driven under the biasof spring 136 to their fully opened positions in preparation for a next succeeding photographic cycle. As plunger of solenoid 172 commences its outward movement, rod of switch S is released to permit the switch to assume its C-A condition.

CONTROL CIRCUIT FLASH MODE CYCLE The control system of camera 10 converts to a follow-focus-type flash operation when a flash array such as that depicted at 234 in FIG. 1 is mounted upon exposure housing 16. As described in connection with function block 236 of FIG. 4, when somounted, a switch S connected within line 424 is closed (FIG. B). Referring additionally to FIGS.'11 and 12, it may be seen that, at the commencement of a photographic cycle under flash mode operation, Event No. 1 remains the same as operation under ambient conditions. Accordingly, input conditions are imposed upon GATES A and B to effect the energization of excitation winding 174 of solenoid 172. As noted at function block 210 of FIG. 4, blades 140 and 142 of exposure mechanism 66 are driven to a blocking terminal position and switch S remained in a GA condition wherein a flash sequencing and firing circuit 476 was energized from primary power line 338, line 364 and line 478. Ground connection for circuit 476 is provided through line 480. Firing circuit 476 is operative to sequentially ignite the individual flashlamps within linear flashlamp arrays as shown at 234 in FIG. 1. Typical of such circuits is one described in a US. Pat. No. 3,618,492, by S. Ellin. Such circuits are necessarily involved and if not appropriately isolated, may be prone to cause spurious flashlamp ignitions in the presence'of excessive electrical noise. Such noise may be present in automaticcameras 

1. A control system for photographic apparatus of a variety having an electrical power supply comprising: instrumentality means for carrying out, when regulated, select operational events of photographic cycles for flash and ambient illuminative modes and including exposure mechanism means actuable to selectively unblock and block an optical path to define an exposure phase of said cycles; light sensitive circuit means responsive to the brightness of a scene for selectively actuating said exposure mechanism means; firing circuit means energizable from said power supply and actuable to effect the ignition of a flashlamp for illuminating a scene; control means for regulating said instrumentality means to carry out a select one of said photographic cycles and operative, during said flash mode, to selectively actuate said exposure mechanism means and said firing circuit means during said cycle exposure phase and to disable said light sensitive circuit means at a select point in time following the commencement of said cycle exposure phase.
 2. The control system of claim 1 in which said control means is operative to disable said light sensitive circuit means only in response to the said ignition of a said flashlamp.
 3. The control system of claim 1 in which said control means is operative to disable said light sensitive circuit means at a select point in time following the said actuating of said firing circuit means.
 4. The control system of claim 1 in which: said firing circuit means is configured to derive a unique output signal condition following the ignition of a said flashlamp; and said control means includes means responsive to said signal condition for disabling said light sensitive circuit means.
 5. The control system of claim 4 wherein said means responsive to said signal condition is present as an electronic switch.
 6. The control system of claim 1 in which: said firing circuit means comprises flashlamp switching logic network means actuable to selectively ignite a said flashlamp, monitoring means having a condition responsive to the ignition of a said flashlamp, and latch means for deriving a unique output signal in response to said monitoring means condition; and said control means includes means responsive to said signal condition for disabling said light sensitive circuit means.
 7. The control system of claim 6 wherein said means responsive to said unique output signal is present as an electronic switch.
 8. The control system of claim 1 wherein said control means includes means operative to de-energize said firing circuit means in response to actuation of said exposure mechanism means effecting the said blocking of said optical path.
 9. A control system for photographic apparatus comprising: instrumentality means for carrying out, when regulated, select operational events of photographic cycles for flash and ambient illuminative modes, said cycles including a pre-exposure operational phase, an exposure operational phase and a post-exposure operational phase, said instrumentality means including electromagnetic actuators selectively energizable and de-energizable to derive said cycle operational phases in a predetermined order; firing circuit means actuable when enabled to effect the ignition in predetermined sequence of a flashlamp within an array of flashlamps oriented for illuminating a photographic subject; and control means for selectively regulating said instrumentality means automatically to carry out sAid operational phases in said predetermined order, and being operative during a said flash illuminative mode cycle to effect the acutation of said firing circuit means when said electromagnetic actuators are in a de-energized condition.
 10. The exposure control system of claim 9 in which said control means operative to effect de-energization of said firing circuit means substantially throughout said pre-exposure and post-exposure operational phases.
 11. The exposure control system of claim 9 in which: said instrumentality means includes a motor selectively actuable by said control means during said pre-exposure and post-exposure phases; and said control means is operative to effect the disabling of said firing circuit means when said motor is actuated.
 12. The exposure control system of claim 9 in which: said instrumentality means includes exposure mechanism means movable to terminal and open positions respectively to block and unblock an optical path; and said control means includes transducer means responsive to said exposure means movement to said terminal position to effect disabling of said firing circuit means.
 13. The exposure control system of claim 12 in which said transducer means is responsive substantially to the commencement of movement of said exposure mechanism means from said terminal toward said open position for enabling said firing circuit means.
 14. The exposure control system of claim 9 in which: said instrumentality means includes: exposure mechanism means having at least one element movable along a given locus of travel from a closed terminal position blocking an exposure aperture toward an open terminal position unblocking said aperture to initiate a photographic exposure and returnable to said closed terminal position to terminate said exposure, and electromagnetic actuator means energizable during said flash mode to effect the arresting of said element at a select position within said locus of travel; said control means includes: transducer means responsive to said exposure mechanism means element movement from said closed terminal position for effecting the enablement by energization of said firing circuit means, means selectively de-energizing said electromagnetic actuator means; and said firing circuit means includes means responsive to said electromagnetic actuator means de-energization for effecting said actuation to ignite a said flashlamp.
 15. The exposure control system of claim 14 in which said transducer means is responsive to said exposure mechanism means element return toward said closed terminal position to effect de-energization of said firing circuit means.
 16. The exposure control system of claim 15 in which said transducer means is configured and arranged to effect said firing circuit means energization and de-energization when said exposure mechanism means element is closely proximate said closed terminal position.
 17. The exposure control system of claim 14 in which: said instrumentality means include electromagnetic exposure actuator means energizable to effect said element movement into said closed terminal position, and means biasing said element to move toward said open terminal position; and said control means includes: means establishing a first signal condition for de-energizing said electromagnetic exposure actuator means to initiate said exposure phase; and said selective de-energizing means includes a delay network actuable in response to said first signal condition and deriving a second signal condition following a delay period selected substantially in correspondence with the inter-terminal position travel time of movement of said exposure mechanism element under drive from said biasing means.
 18. The exposure control system of claim 17 in which said transducer means is reponsive to said exposure mechanism means element return toward said closed terminal position to effect de-energization of said firing circuit mEans.
 19. The exposure control system of claim 14 in which: said firing circuit means is configured to derive a unique signal condition following the ignition of said flashlamp; and said control means includes flash timing means actuable in response to said unique signal condition for effecting the said exposure mechanism means element movement into said closed terminal position at the termination of a select period of time following said flashlamp ignition.
 20. The exposure control system of claim 19 in which said flash timing means period of time is selected in correspondence with the period of light output generation of said flashlamp.
 21. A control system for photographic apparatus comprising: instrumentality means for carrying out, when regulated, select operational events of photographic cycles for transient and ambient illuminative modes and including exposure mechanism means actuable to selectively unblock and block an optical path to define an exposure phase of a said cycle; light sensitive circuit means responsive to the light levels of a scene for selectively actuating said exposure mechanism means to block said optical path; firing circuit means actuable when enabled to effect the ignition of a flash lamp and having a unique signal condition subsequent to a said ignition; and control means for regulating said instrumentality means to carry out a select one of said photographic cycles and for selectively enabling and disabling said light sensitive circuit means and said firing circuit means, said control means including timing means responsive during said transient illuminative mode to said unique signal condition for actuating said exposure mechanism means to block said optical path following a predetermined interval of time.
 22. The control system of claim 21 wherein said control means is operative to disable said light sensitive circuit means only in response to the said ignition of a said flashlamp.
 23. The control system of claim 21 in which said control means is operative to disable said light sensitive circuit means at a select point in time following said actuation of said firing circuit means.
 24. The control system of claim 21 in which said control means is responsive to said unique signal condition for disabling said light sensitive circuit means.
 25. The control system of claim 21 in which said firing circuit means comprises: flashlamp switching means for selectively igniting a said flashlamp; monitoring means having a condition responsive to the ignition of a said flashlamp; and latch means for deriving said unique signal condition in response to said monitoring means condition.
 26. A photographic exposure control system for apparatus for exposing photographic material with either ambient or flash illumination, said system comprising: means for alternately blocking and unblocking such exposure path; for initiating an exposure cycle including means for actuating said blocking and unblocking means so as to unblock such exposure path; a light sensitive element; normally inoperative means responsive to a predetermined amount of illumination incident on said light sensitive element for actuating said blocking and unblocking means to block said path following the unblocking thereof; means responsive to the initiation of such exposure cycle for first activating said light responsive means and for subsequently, after a lapse of a predetermined time following the initiation of such exposure cycle, activating a source of illumination; and means responsive to the activation of such a source of illumination for precluding further operation of said light responsive means and for actuating said blocking and unblocking means to block such exposure path whereby said light responsive means operates to cause the blocking of such exposure path if, during the lapse of said predetermined time following initiation of such exposure cycle, said predetermined amount of ambient light is incident on said light sensitive element and said means responsive to the activation of such a source of illumination operates to cause the blocking of such exposure path if, during the lapse of said predetermined time following initiation of such exposure cycle, said predetermined amount of ambient light is not incident upon said light sensitive element.
 27. A photographic exposure control system for apparatus for exposing photographic material with either ambient or flash illumination, said system comprising: means for alternately blocking and unblocking such exposure path; means for initiating an exposure cycle including means for actuating said blocking and unblocking means so as to unblock such exposure path; a light sensitive element; normally inoperative means responsive to a predetermined amount of illumination incident on said light sensitive element for actuating said blocking and unblocking means to block said path following the unblocking thereof; means responsive to the initiation of such exposure cycle for first activating said light responsive means and for subsequently, after a lapse of a predetermined time following the initiation of such exposure cycle, activating a source of illumination; and means responsive to the activation of such a source of illumination for precluding further operation of said light responsive means and for actuating said blocking and unblocking means to block such exposure path after a lapse of a predetermined time following the commencement of such activation of such a source of illumination whereby said light responsive means operates to cause the blocking of such exposure path if during the lapse of said predetermined time following initiation of such exposure cycle, said predetermined amount of ambient light is incident on said light sensitive element and said means responsive to the activation of such a source of illumination operates to cause the blocking of such exposure path if, during the lapse of said predetermined time following initiation of such exposure cycle, said predetermined amount of ambient light is not incident upon said light sensitive element.
 28. The system of claim 27 wherein said light responsive means includes means responsive to said light sensitive element for charging to a predetermined voltage level as a function of said incident light and a normally operative shunt for said charging means, said means for activating said light responsive means includes means rendering said shunt inoperative, and said means for precluding further operation of said light responsive means including means for rendering said shunt operative.
 29. Photographic exposure control system for exposing photographic material with either ambient or flash illumination, said system comprising: means for varying the amount of illumination transmitted along a given exposure path including means for alternately blocking and unblocking such exposure path; means responsive to the lapse of a predetermined time following the unblocking of such exposure path for activating a source of flash illumination; means responsive to scene light for regulating said varying means in accordance with ambient illumination; and means independent of said light responsive means and responsive to the lapse of a predetermined amount of time following the unblocking of such exposure path for regulating said varying means in accordance with flash illumination, and means responsive to the activation of such a source of illumination for precluding regulation by said light responsive means subsequent to the activation of such a source of illumination whereby said light responsive means operates to regulate said varying means prior to the lapse of said predetermined time and said means independent of said light responsive means operates to solely regulate said varying means following the lapse of said predetermined time.
 30. Apparatus for carrying out a plurality of operational phases of a photographic proGram including a pre-exposure operational phase, an exposure operational phase, and a post-exposure operational phase, said apparatus comprising: normally inoperative means for activating a source of illumination responsive to being energized from a source of electrical power and simultaneously therewith or subsequently thereto receiving of a predetermined trigger signal; means for energizing said activating means; means for providing said predetermined trigger signal to said activating means; and means for rendering said energizing means inoperative during such pre-exposure and post-exposure phase so as to preclude inadvertent activation of such a source of illumination during such pre-exposure and post-exposure phases responsive to spurious signals.
 31. The apparatus of claim 30 wherein such preexposure phase includes the termination of a scene viewing operation and such post-exposure phase includes a film processing operation.
 32. The apparatus of claim 30 wherein said rendering means includes means responsive to the activation of such a source of illumination.
 33. A photographic exposure control system for use with a source of artificial illumination for exposing photographic material, said system comprising: means for blocking and unblocking an exposure path; normally inoperative means for activating a source of illumination responsive to being energized from a source of electrical power and simultaneously therewith or subsequently thereto receiving of a predetermined trigger signal; means for energizing said activating means; means for providing said predetermined trigger signal to said activating means when said activating means is energized and such exposure path is unblocked; and means for rendering said energizing means inoperative responsive to the lapse of a predetermined interval of time after the commencement of the activation of such source illumination to de-energize said activating means and thereby preclude current flow to said activating means from such source of electrical power and preclude spurious signals from inadvertently activating such a source of illumination subsequent to the lapse of such a predetermined interval of time.
 34. The control system of claim 33 wherein said means for rendering said energizing means inoperative includes a time delay circuit which is responsive to activation of such a source of illumination.
 35. The control system of claim 33 wherein said energizing means includes a means responsive to the blocking and unblocking of such exposure path for respectively uncoupling and coupling such source of power to said activating means, said means for rendering said energizing means inoperative includes means responsive to the lapse of such a predetermined interval for actuating said blocking and unblocking means following the unblocking of such exposure path to block such exposure path whereby said coupling and coupling means is actuated to uncouple such source from said activating means.
 36. A photographic exposure control system for use with a source of artificial illumination for exposing photographic material, said system comprising: means for blocking and unblocking an exposure path; normally inoperative means for activating a source of illumination responsive to being energized from a source of electrical power and simultaneously therewith or subsequently thereto receiving of a predetermined trigger signal; means for energizing said activating means; means for providing said predetermined trigger signal to said activating means when said activating means is energized and such exposure path is unblocked; and means for rendering said energizing means inoperative responsive to the lapse of a predetermined amount of time following the activation of such source of illumination to de-energize said activating means and thereby preclude current flow to said activating means from such source of electrical power and preclude spurious signals from inadvertentLy activating such a source of illumination subsequent to the lapse of such a predetermined interval of time.
 37. A photographic exposure control system for exposing photographic material with artificial illumination comprising: means for alternately blocking and unblocking an exposure path; normally inoperative means for activating a source of illumination responsive to being energized from a source of electrical power and simultaneously therewith or subsequently thereto receiving of a predetermined trigger signal; means for energizing said activating means responsive to unblocking of said exposure path; and means for providing said predetermined trigger signal to said activating means.
 38. The system of claim 37 additionally including means responsive to the activation of such a source of illumination for rendering said energizing means inoperative so as to de-energize said activating means.
 39. A photographic exposure control system for use with apparatus having means defining an exposure path for exposing photographic material with flash illumination, said system comprising: means for selectively blocking and unblocking such exposure path; means for initiating an exposure cycle including means for actuating said blocking and unblocking means to unblock such exposure path; means for activating a source of flash illumination; and means for actuating said blocking and unblocking means after the unblocking of such exposure path to block said path responsive to the lapse of a predetermined time after the commencement of activation of such a source of illumination, said actuating means includes a trigger circuit configured for actuating said blocking and unblocking means to block such path in response to a given trigger signal, means responsive to the activation of such a source of illumination for producing such given trigger signal, and means for connecting said activation responsive means to said trigger circuit and for delaying the conduction of such trigger signal thereto for said predetermined lapse of time following the production of such trigger signal.
 40. A flash firing circuit for use in an artificial light exposure control system of a photographic camera, such control system having means responsive to a unique signal for performing a function associated with the operation of such camera, said circuit comprising: first terminal means configured for coupling to a source of electrical power; a plurality of lamp switching circuits connected to said first terminal means, each of said lamp switching circuits including second terminal means for releasable electrical connection to one of a plurality of flash lamps and means for rendering its respective lamp switching circuit conductive when one of such lamps is coupled to its respective second terminal means; control means responsive to a predetermined trigger signal for sequentially actuating each of said conductive rendering means in a predetermined order of first to last so as to sequentially activate each such lamp; and means coupled to said switching circuits for providing such a unique signal upon activation of one of such lamps whereby such unique signal is made available to such exposure control system to initiate the performance of such function.
 41. The firing circuit of claim 40 wherein said means for providing such a unique signal is responsive to activation current flowing in one of said lamp switching circuits.
 42. The firing circuit of claim 40 additionally including means responsive to such unique signal for precluding actuation of any of said conductive rendering means.
 43. The firing circuit of claim 40 wherein said first terminal means includes a current sensing element in series with said switching circuits, and said means for providing such a unique signal includes means responsive to said current sensing element for producing a high level voltage when said activation current is flowing in one of said lamp switching circuiTs.
 44. The firing circuit of claim 43 wherein said means for producing a high level voltage includes a transistor element coupled to said first terminal means and said current sensing element so as to be reverse biased when currents less than such activation current flows in any one of said switching circuits and forward biased when a current approximately equal to or greater than such activating current flows in said switching circuits. 